In a written work, is it better to reference people by their first or last name?

Question

In a work, when you introduce someone by their full name and later refer to them in a context which is not appropriate for a pronoun, do you use their first or last name?Example: "Eli Whitney is credited with inventing the concept of interchangeable parts. [...] Out of this contract, **(Eli or Whitney)** developed a sample of guns which he then presented to the United States Congress"

Answer 1

In academic writing, you usually use the person's last name to refer to them after you've introduced them with their full name. This is also true in journalism.

In creative writing, however, authors may choose to refer to their characters however they'd like.